SEATTLE — The arrival of a new CEO at the world's largest charitable foundation comes with much less fanfare than Bill Gates' own decision to leave Microsoft Corp. to focus more on his family's philanthropy.

Jeff Raikes, 50, a former top executive at the software giant, will be the Bill & Melinda Gates Foundation's second leader since its inception in 1997. He is replacing Patty Stonesifer, another former Microsoft exec and friend of Bill and Melinda Gates, who announced in February that she would step down.

Raikes will start his job Tuesday in silence, as the charity has denied requests for media interviews in order to give him 100 days of solitude to focus on his new job.

But Raikes has shared his perspective about the new position in several recent interviews with The Associated Press.

"I'm absolutely thrilled to be joining the Gates Foundation," Raikes said. "This is truly a dream job."

In July, Bill Gates stepped away from his daily duties at the software company he co-founded to focus on the work of his $38 billion foundation. His wife, Melinda, also has stepped up her time commitment to the foundation.

Raikes has known Bill Gates since starting at Microsoft in 1991, and he says he's learned a lot about the foundation over the years. He expects some of his biggest challenges to be getting up to speed as quickly as possible and managing the foundation's rapid growth.

The foundation could add as many as 200 new employees to its existing staff of nearly 600 in the second half of 2008, Raikes said.

In the past decade, the foundation has given away more than $16 billion, mostly in global health, global development and U.S. education.

It has been ramping up its giving since Warren Buffett, head of Omaha, Neb.-based Berkshire Hathaway, announced in June 2006 that he would make annual donations of about $1.5 billion to the foundation, with the money to be distributed in the year it is donated.

The breadth of its work seemed a little overwhelming to Raikes at first, with three key program areas and 22 initiatives.

"All have very significant — some would say audacious — goals," he said.

Until this year, he was president of Microsoft's business software division, responsible for such things as the Office software suite, Microsoft's server software, and applications that help businesses track customers and business processes.

In addition to his years in business management, his volunteer work with various nonprofit organizations focusing on education and children's issues give him many of the skills he will need to the run the foundation.

He and his wife, Tricia, formed the Raikes Foundation in 2002 to support youth development, education and community issues in the Seattle area. He joined other Seattle business leaders in 1992 to buy the Seattle Mariners baseball club.

While planning for his retirement from Microsoft this year, he became intrigued by the Gates Foundation's efforts to spark a "green revolution" in Africa. He considered getting involved in agribusiness because of his background growing up on a family farm near Omaha.

When the outgoing Stonesifer announced she was stepping down, Raikes started thinking he might have a less restful retirement.

"The foundation is in very strong shape. Patty has been an excellent leader," Raikes said. "I feel very comfortable coming into this role and building onto the success she's had."

Stonesifer also expressed confidence in Raikes in a recent interview.

"Everything I've seen so far indicates he's going to be fantastic," said Stonesifer, who worked at Microsoft at the same time as Raikes but never in the same department.

"It is a great time, actually, to be passing on the CEO," she added, "and Jeff's got the energy and passion and the partnership with Bill and Melinda to really do a fabulous job at it."